In recent years discoloured water has become a matter of growing concern to water resource managers. Discoloured water is a major source of consumer complaints and is expensive in capital and recurrent costs. The treatment of water discolouration is believed to be associated with a number of health issues, such as Alzheimer's disease. In particular, discoloured water, upon chlorination, is believed to produce carcinogens. The principal aim of this research has been to consider and manage water colour within an entire reservoir catchment system; Thornton Moor Reservoir, the study area, has experienced some of the highest values of colour in the Yorkshire Water Region, and has been an area of significant concern and cost to Yorkshire Water Services. Apparently homogenous subcatchments can produce marked differences in the colour of runoff data. This research has involved an investigation into the relationship between the subcatchment tributary water colour and catchment morphology. The relationships established were used to generate a predictive model for water colour such that areas of high water colour could be identified without intensive sampling. The initial phase of this study considered the transfer network involved in bringing the colour from the catchment to the reservoir. This has involved an analysis of the spatial and temporal variation of water discolouration within the catchment. The consistency of the spatial variation of water colour between the tributaries has been utilised to develop a management protocol which is presently being implemented at Thornton Moor in order to minimise the level of discolouration, whilst maintaining water supplies. Edwards (1987), describes the reservoir as the second line of defence in the protection of water supplies in direct supply reservoirs. No research to date has considered the role of the reservoir in the storage, transmission and release of discoloured water. Empirical evidence at Thornton Moor Reservoir suggests that for the majority of the year, the reservoir operates as a buffer to colour; however at certain times of the year it appears actively to increase the colour entering the treatment works. In considering the entire catchment system, it has been possible to develop a transferable staged approach to catchment management.

No description available.

There is a requirement in the European Union to divert organic wastes from landfill because of the risk of methane emissions. One alternative is anaerobic digestion of organic wastes, such as food waste, to stabilise them whilst at the same time recovering the energy from them. One problem with this approach is that the high nitrogen content of food waste may lead to ammonia inhibition. A solution to this has been found for mesophilic digestion but had not been attempted in thermophilic digestion where ammonia toxicity is known to be more acute. The work was carried out in laboratory-scale semi-continuous digesters operated over long time periods to provide maximum opportunity for acclimatisation, and in duplicate to give an indication of reproducibility. A series of experimental runs were undertaken at thermophilic temperatures to assess the influence of trace element (TE) addition on the digestion process. These were carried out at organic loading rates (OLR) of 2, 3 and 4 g volatile solids (VS) l-1 day-1 against unsupplemented controls at OLR 2 g VS l-1 day-1. Although TE addition could offset the accumulation of VFA which occurred in response to an increasing concentration of total ammonical nitrogen (TAN), it could not prevent this. The high alkalinity resulting from ammonia, however, allowed the digesters to continue to produce methane until VFA had accumulated to high concentrations before eventual failure due to a rapid drop in pH. To determine the threshold inhibitory ammonia concentration in thermophilic digestion, one pair of digesters was run on synthetic low nitrogen food waste (low-N food waste) at an OLR 2 g VS l-1 day-1 and compared to a control pair running on domestic food waste at the same loading. All four digesters received TE supplementation. The digesters fed with low-N food waste showed consistently stable performance with pH ~7.4, IA/PA ratio ~0.4-0.5, SMP 0.39 l CH4 g-1 VS, 52-55% CH4, total VFA <500 mg l-1 and 88% VS destruction whereas the controls showed signs of failure after 112 days and irreversible VFA accumulation at a TAN concentration >3.5 g N l-1. One of the low N digesters was supplemented with urea slowly and one by a shock dose: both showed signs of VFA accumulation at TAN >2.5 gl-1 and, again, an irreversible trend in propionic acid build-up when TAN >4 g N l-1. Long term operation showed meta-stable conditions when the digesters were operated at TAN between 2.5 - 3.5g l-1 with oscillations in VFA (especially propionic acid) concentration. Mesophilic digestion at 37oC with TE addition showed very stable performance with pH ~8, IA/PA ≤ 0.3, SMP ~0.48 l CH4 g-1 VS, 55-60% CH4, total VFA < 300 mg l-1 and VS destruction ~75-78% with a final total ammonia nitrogen (TAN) concentration of 4.5 g N l-1. As the temperature in digesters was raised from 35 to 43 oC in 1oC steps a change in performance was noted when the temperature reached 40 oC. Above this temperature VFA concentrations rose above 4000 mg l-1 and biogas and methane production fluctuated. It is probable that the higher temperature increased the concentration of free ammonia nitrogen (FAN) to ~800 g N l-1 at the measured TAN concentration ~5.5-6.0 g N l-1 and this was sufficient be inhibitory even with TE dosing. Fluorescent in situ hybridisation (FISH) was used to identify the methanogenic populations in some of the trials over selected time periods. This showed changes in population structure both in relation to temperature (mesophilic or thermophilic) and also in response to increasing concentrations of TAN. At high TAN concentrations Methanomicrobiales was the dominant methanogenic group and under mesophilic conditions this proved to be extremely ammonia tolerant. A 14C radio-labelling assay confirmed the dominant pathway to methane formation was by the hydrogenotrophic route which reflected the known metabolic pathway of this methanogen. It was concluded that thermophilic digestion of source segregated domestic food waste would lead to instability and failure of the process unless measures were introduced to reduce the TAN concentration to < 3.5 g N l-1, and preferably to < 2.5 g N l-1. Keywords: Anaerobic digestion, food waste, biogas, VFA accumulation, ammonia inhibition, Fluorescent in situ Hybridisation (FISH).

Due to legislative pressures and the recent ban of trybutyl tin, alternative environmentally acceptable ship hull antifouling systems are required. This thesis uses a multidisciplinary approach to combine two disparate areas of research namely marine biology and surface engineering, to develop a novel natural product (NP) based antifouling system. The overall objective of this thesis is to transfer a natural marine biological defence mechanism into an engineered antifouling coating system. By combining natural product extraction and incorporation into a trial coating an extensive test programme was able to investigate the antifouling performance and address the issues of bringing this active area of research to the next technological readiness level. By using a stepwise approach to the development of the engineered solution, a suite of techniques were used to fully characterise a NP based system. The biological and surface engineering techniques adapted and developed are described here and their future use to evaluate a novel NP based antifoulant system is critically assessed. After an extensive literature review, an ethanol extract from the red seaweed Chondrus crispus was selected as the natural product source. NP specimens were harvested locally and also purchased as industrially processed dried algae. The industrially processed algae showed good antifoulant activity ( ≤ 25 μg mL-1) in laboratory bioassays and had a greater efficacy than the locally harvested samples highlighting its potential as an economically viable solution. The direct incorporation of the NP into a commercial control depletion polymer binder, allowed for the rapid development of characterisation techniques to evaluate the effects this had on the performance of the NP-binder matrix. The feasibility of a range of electrochemical techniques to measure corrosion potential, impedance, resistance and water uptake in the NP coating was critically assessed. A combination of open-circuit potential and electrochemical impedance spectroscopy provided a unique and rapid means to non-destructively measure the contribution of incorporated NPs to the degradation and water uptake of the binder film. Studies of biofilm growth were used to successfully measure community viability and structure using fluorescent staining and differential interference contrast microscopy. These techniques were found to be very informative on Southampton water marine biofilm community structure and were cross correlated by fourier transform infrared measurements. Resistance to biofouling was determined through field trials, an important testing platform for an antifouling system, and specifically trials which test the entire coated system including any primers and substrate preparation requirements. An initial NP antifouling performance greater than the booster biocide (Chlorothalonil) control was documented for one field trial over a period of the first 6 weeks. A key aspect was to determine the potential efficacy of NPs and their viability in a coating system. To achieve this, a range of standard and non-standard techniques were used to assess this novel combination of crude NP extract and commercial binder system. This work has shown that a limited antifoulant activity is achievable. By evaluating the effect of a NP on both the fouling community and a binder system this unique approach helps define key techniques to assess future NP antifoulants and identifies the optimisation required to increase their functionality.

No description available.

No description available.

No description available.

Este trabalho tem por objetivo o desenvolvimento de métodos numéricos eficientes, tanto no domínio do tempo quanto na freqüência, para a modelagem da propagação de ondas em estruturas que apresentem combinações de meios convencionais e/ou metamateriais, particularmente os metamateriais onde tanto a permissividade quanto a permeabilidade são simultaneamente negativos. Em alguns casos à simulação de tais estruturas representa um grande desafio em virtude da grande demanda computacional requerida. Uma forma eficiente de se contornar este problema é a utilização de técnicas de divisão de operador, com destaque para a técnica implícita das direções alternadas (ADI), já amplamente explorada nos domínios do tempo e da freqüência, e mais recentemente a técnica localmente unidimensional (LOD). A técnica LOD é utilizada com destaque neste trabalho, onde pela primeira vez esta foi empregada em um método de propagação de feixe de ângulo largo em diferenças finitas no domínio da freqüência, o qual foi denominado por LOD FD-BPM. O passo seguinte foi estender sua aplicação para o domínio do tempo, sendo a primeira abordagem empregada em um método de propagação de onda em diferenças finitas no domínio do tempo, denominado por LOD TD-WPM. Em seguida, a técnica LOD foi aplicada ao método FDTD resultando em um formalismo implícito, denominado LOD-FDTD, o qual apresenta uma maior eficiência computacional do que o tradicional ADI-FDTD. Estas abordagens apresentaram uma excelente eficiência computacional em virtude da possibilidade de utilização de passos de tempos maiores do que o permitido pela condição de estabilidade de Courant-Friedrich-Levy (CFL), além de serem incondicionalmente estáveis como conseqüência da aplicação do esquema de Crank-Nicolson (CN). A restrição do método LOD-FDTD, referente à sua precisão de apenas primeira ordem no tempo, foi contornada com o uso do esquema de divisão de operadores conhecido como Strang splitting (SS), resultando no método de segunda ordem no tempo LOD-FDTD-SS. Os métodos FDTD, ADI-FDTD, LOD-FDTD e LOD-FDTD-SS foram também implementados com base no modelo de Drude com perdas, possibilitando, assim, uma modelagem adequada de meios metamateriais. Outra contribuição importante deste trabalho foi à implementação da condição de contorno split PML no formalismo LOD-FDTD para a simulação de problemas eletromagnéticos abertos. / This work focuses on developing efficient numerical methods, both in time and frequency domains, for modeling wave propagation in structures that present conventional media and/or metamaterial media combinations, particularly the metamaterials where both permeability and permittivity are simultaneously negative. In some cases, the simulation of such structures represent a great challenge, due to the great computational requirements. An efficient way of solving this problem is the usage of operator splitting techniques, specifically the alternate direction implicit (ADI) technique, already explored both in time and frequency domains, and recently the locally one-dimensional (LOD) . This work dedicates special attention to the LOD technique, where, for the first time, this one was applied in a finite difference frequency domain wide-angle propagation method, which was denominated LOD FD-BPM. The next step was to extend its application to the time domain, the first approach was used in a finite difference time domain wave propagation method, denominated LOD TD-WPM. Next, the LOD technique was applied to the FDTD method, resulting in an implicit formalism, denominated LOD-FDTD, which presents a better computational efficiency than the traditional ADI-FDTD. These approaches present an excellent computational efficiency, due to the possibility of using greater time steps than those permitted by the Courant-Friedrich-Levy (CFL) stability condition, being unconditionally stable as a consequence of applying the Crank-Nicolson (CN) scheme as well. The LOD-FDTD method restriction, referring to its first order accuracy in time, was circumvented by using the operator division scheme known as Strang splitting (SS), resulting in a second order time method LOD-FDTD-SS. The FDTD, ADI-FDTD, LOD-FDTD and LOD-FDTD-SS methods were also implemented with a lossy Drude model, making, this way, possible an adequate metamaterial media modeling. Another important contribution of this work was the implementation of the split PML contour condition in the LOD-FDTD formalism for the simulation of open electromagnetic problems.

A Curcumin há muito tempo é utilizada como condimento, colorífico e na medicina tradicional asiática. Conhecida como açafrão-da-índia, recentemente tem chamado a atenção devido ao grande potencial medicinal. Surgiram trabalhos principalmente sobre seus supostos efeitos benignos no tratamento de câncer e Alzheimer porém não limitados a estas enfermidades. Na tentativa de otimizar as propriedades medicinais surgiu a Dimethoxy Curcumin, um composto sintético que apresenta maior citotoxicidade e estabilidade biológica que a Curcumin. A maioria das reações químicas e biológicas ocorrem em soluções e os efeitos dos solventes são de extrema importância e complexidade. Neste trabalho nós estudamos os efeitos dos solventes ciclohexano e acetonitrila nos espectros de absorção e emissão da Dimethoxy Curcumin. Consideramos a contribuição de diferentes isômeros e estados excitados usando a Teoria do Funcional Densidade Dependente do Tempo (TD-DFT) utilizando a aproximação Modelo Contínuo Polarizável para o solvente. Nós observamos que as energias de emissão dos estados singletos sofrem um deslocamento para o vermelho enquanto que os estados tripletos sofrem um deslocamento para o azul. Respondemos estas questões analisando a variação do momento de dipolo durante a transição. Neste trabalho encontramos boa concordância com os valores experimentais dos espectros de absorção, emissão, deslocamento espectral e deslocamento Stokes. / The Curcumin has long been used as a condiment, pigment and in the traditional Asian medicine. Known as turmeric, recently has attracted attention because of the large medical potential. Several studies were made mainly about the supposed benign effects in the treatment of cancer and Alzheimer but not limited to these diseases. Attempt to optimize their medicinal properties there appeared the Dimethoxy Curcumin, a synthetic compound that has a higher cytotoxicity and biological stability than Curcumin. Most of the chemical and biological reactions occur in solutions and the solvent effects are of great importance and complexity. In the present work, we study the effects of the solvents cyclohexane and acetonitrile in the absorption and emission spectra of Dimethoxy Curcumin. We consider the contribution of various isomers and excited states using the Time Dependent Density Functional Theory (TD-DFT) with the Polarizable Continuum Model (PCM) approximation for the solvent. We observe that the emission energy of the singlet states are red shifted while the triplet states are blue shifted. We address this by analyzing the dipole moment variation after the transition. We find good agreement with the experimental values for the absorption, emission, spectral shift and Stokes shift

A Curcumin há muito tempo é utilizada como condimento, colorífico e na medicina tradicional asiática. Conhecida como açafrão-da-índia, recentemente tem chamado a atenção devido ao grande potencial medicinal. Surgiram trabalhos principalmente sobre seus supostos efeitos benignos no tratamento de câncer e Alzheimer porém não limitados a estas enfermidades. Na tentativa de otimizar as propriedades medicinais surgiu a Dimethoxy Curcumin, um composto sintético que apresenta maior citotoxicidade e estabilidade biológica que a Curcumin. A maioria das reações químicas e biológicas ocorrem em soluções e os efeitos dos solventes são de extrema importância e complexidade. Neste trabalho nós estudamos os efeitos dos solventes ciclohexano e acetonitrila nos espectros de absorção e emissão da Dimethoxy Curcumin. Consideramos a contribuição de diferentes isômeros e estados excitados usando a Teoria do Funcional Densidade Dependente do Tempo (TD-DFT) utilizando a aproximação Modelo Contínuo Polarizável para o solvente. Nós observamos que as energias de emissão dos estados singletos sofrem um deslocamento para o vermelho enquanto que os estados tripletos sofrem um deslocamento para o azul. Respondemos estas questões analisando a variação do momento de dipolo durante a transição. Neste trabalho encontramos boa concordância com os valores experimentais dos espectros de absorção, emissão, deslocamento espectral e deslocamento Stokes. / The Curcumin has long been used as a condiment, pigment and in the traditional Asian medicine. Known as turmeric, recently has attracted attention because of the large medical potential. Several studies were made mainly about the supposed benign effects in the treatment of cancer and Alzheimer but not limited to these diseases. Attempt to optimize their medicinal properties there appeared the Dimethoxy Curcumin, a synthetic compound that has a higher cytotoxicity and biological stability than Curcumin. Most of the chemical and biological reactions occur in solutions and the solvent effects are of great importance and complexity. In the present work, we study the effects of the solvents cyclohexane and acetonitrile in the absorption and emission spectra of Dimethoxy Curcumin. We consider the contribution of various isomers and excited states using the Time Dependent Density Functional Theory (TD-DFT) with the Polarizable Continuum Model (PCM) approximation for the solvent. We observe that the emission energy of the singlet states are red shifted while the triplet states are blue shifted. We address this by analyzing the dipole moment variation after the transition. We find good agreement with the experimental values for the absorption, emission, spectral shift and Stokes shift